Color profile: Disabled Composite 150 lpi at 45 degrees NAT. CROAT. VOL. 18 No 1 39–48 ZAGREB June 30, 2009 original scientific paper / izvorni znanstveni rad ARANEUS ALSINE (WALCKENAER, 1802), (ARANEIDAE, ARANEAE, ARACHNIDA) – A RARE AND LIKELY THREATENED SPIDER OF THE CROATIAN FAUNA ANDREJA BRIGI]1,ANTUN ALEGRO2 &VEDRAN [EGOTA2 1Department of Zoology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, Zagreb, Croatia (e-mail: [email protected]) 2Department of Botany, Faculty of Science, University of Zagreb, Maruli}ev trg 20/II, Zagreb, Croatia Brigi}, A., Alegro, A. & [egota, V.: Araneus alsine (Walckenaer, 1802), (Araneidae, Araneae, Arachnida) – a rare and likely threatened spider of the Croatian fauna. Nat. Croat., Vol. 18, No. 1, 39–48, 2009, Zagreb. The present paper deals with the distribution of Araneus alsine (Walckenaer, 1802) (syn.: Epeira alsine Walckenaer, 1805; E. lutea C. L. Koch, 1837) in Croatia and its habitats based on literature data, museum collections and field findings. The spider A. alsine was captured in Croatia’s most di- verse and oldest peatland, the \on Mo~var Botanical Reserve at Blatu{a. The biology, ecology and threat status of A. alsine are discussed. Key words: Araneus alsine, Araneidae, Croatia, distribution, peatland, \on Mo~var Botanical Reserve Brigi}, A., Alegro, A. & [egota, V.: Araneus alsine (Walckenaer, 1802), (Araneidae, Araneae, Arachnida) – rijetka i vjerojatno ugro`ena vrsta pauka u hrvatskoj fauni. Nat. Croat., Vol. 18, No. 1, 39–48, 2009, Zagreb. U radu je navedena rasprostranjenost i tip stani{ta pauka Araneus alsine (Walckenaer, 1802) (syn.: Epeira alsine Walckenaer, 1805; E. lutea C. L. Koch, 1837) u Hrvatskoj, koji su izra|eni na temelju literaturnih podataka, podataka iz muzejske zbirke i terenskih opa`anja. Pauk A. alsine je ulovljen na najraznolikijem i najstarijem cretu u Hrvatskoj, u botani~kom rezervatu \on mo~var, Blatu{a. U radu se raspravlja o biologiji, ekologiji i statusu ugro`enosti vrste A. alsine. Klju~ne rije~i: Araneus alsine, Araneidae, Hrvatska, rasprostranjenost, cret, botani~ki rezervat \on Mo~var INTRODUCTION In the past, the spider fauna of Croatia was poorly investigated and mainly stud- ied by foreign researchers (KEYSERLING, 1862; THORELL, 1870; CHYZER &KULCZYNSKI, 1892–97; KULCZYNSKI, 1914; DI CAPORIACCO, 1927; REIMOSER, 1929, 1930; ABSOLON & Croatian Natural History Museum, Demetrova 1, Zagreb, Croatia M:\NATURA\natura_1-09\brigic.vp 24. lipanj 2009 9:55:40 Color profile: Disabled Composite 150 lpi at 45 degrees 40 Brigi}, A. et al.: Araneus alsine – a rare and likely threatened spider of the Croatian fauna KRATOCHVIL, 1933; KRATOCHVIL &MILLER, 1939, 1940), though the contribution of local researchers is also significant (JURINAC, 1887; GASPERINI, 1891, 1892; DAMIN, 1896, 1900; LANGHOFFER, 1912, 1915; GIROMETTA, 1914, 1929; POLJUGAN, 1915, RUCNER &RUCNER, 1995). The literature is primarily concentrated on subterranean spider fauna, characterised by the vast number of endemic and relict species (DELTSHEV, 1999; OZIMEC, 2002). The most comprehensive study was undertaken by REIMOSER (1930), DAMIN (1896, 1900) and by NIKOLI] (cf. NIKOLI] &POLENEC, 1981) in the 1950s. NIKOLI] and DAMIN left valuable spider collections. In recent years, the spi- der fauna has only been studied in particular areas of Croatia, e.g. cavernicolous spider fauna (OZIMEC, 2002; PAVLEK, 2006) and the spider fauna of certain protected areas ([TAMBUK &ERBEN, 2002; KATU[I], 2008). According to NIKOLI] &POLENEC (1981) and updated by MILO[EVI] (2002), a total of 643 spider species have been re- corded in Croatia. Due to its great habitat diversity, the relatively poor exploration of certain regions and lately due to a lack of taxonomical experts, new species for the Croatian arachnid fauna could be expected. The orange wheelweaving spider or strawberry spider Araneus alsine (Walckenaer, 1802) is Palaearctic species which, in its European range, is distributed in Britain (ROBERTS, 1996; MERRETT &MURPHY, 2000), Finland (KOPONEN, 2007), Sweden (KRO- NESTEDT, 2001), Norway (AAKRA &HAUGE, 2000), Netherlands & Belgium (VAN HELS- DINGEN, 1999; BOSMANS &VANUYTVEN, 2001; TUTELAERS, 2008), Denmark (SCHARFF & GUDIK-SØRENSEN, 2006), Switzerland (MAURER &HÄNGGI, 1990), France (CANARD, 2005), Germany (PLATEN et al., 1995), Austria (KOMPOSCH &STEINBERGER, 1999; KOM- POSCH, 2000), Italy (PESARINI, 1995), Slovenia (POLENEC, 1967, 1968; KUNTNER &KOSTANJ- [EK, 2000), Hungary (SAMU &SZINETÁR, 1999), Czech Republic (BUCHAR &RUg@I^KA, 2002), Slovakia (GAJDOS et al., 1999; KORENKO, 2004), Poland (STAREzGA, 2004), Serbia (NIKOLI] &POLENEC, 1981; DELTSHEV,]UR^I] &BLAGOEV, 2003), Bulgaria (BLAGOEV, 2002), Romania (FUHN &OLTEAN, 1970) and Turkey (TOPCU et al., 2005). A. alsine has an unmistakable appearance, thanks to the colour of abdomen and legs, which can vary from pale orange to deep purplish-red (ROBERTS, 1996). There are conspicuous pale yellow spots on the dorsal side of abdomen. The spider builds small webs near the ground and waits nearby in one or two dried leaves that it has rolled together with silk or are naturally curled (PLATNICK, 2008). According to ROB- ERTS (1996) and BIERWIRTH (1998), adult spiders can be found in June and July, and adult females still in September. The objective of this paper is to determine the distribution of A. alsine in Croatia based on literature data, museum collections and field observations and to give fur- ther information on its habitat. MATERIALS AND METHODS Study area The \on Mo~var Botanical Reserve is situated in central Croatia (Fig. 1), at an al- titude of 130 m, and it phytogeographically belongs to the zone of Illyrian sessile oak-hornbeam forests (Epimedio-Carpinetum betuli). Covering an area of 10 ha, this M:\NATURA\natura_1-09\brigic.vp 24. lipanj 2009 9:55:40 Color profile: Disabled Composite 150 lpi at 45 degrees Nat. Croat. Vol. 18(1), 2009 41 represents the one of the largest and oldest (GIGOV &NIKOLI], 1960) peatland area in Croatia. It encompasses a mosaic of rare mire vegetation types – from fens (ass. Caricetum lasiocarpae) and intermediate bogs (ass. Drosero-Caricetum stellulatae and Rhynchosporetum albae) to fragments of raised bogs (stands of Sphagnum capillifolium/ Sph. palustre-Polytrichum longisetum). In addition to the downy birch (Betula pubescens), in the process of succession, the peatland is inhabited by silver birch (B. pendula) and other three and shrub species. The eastern and southern edges of the area are bordered by swamp forests and alder shrubs (Carici elongatae-Alnetum glutinosae). Field data The orange wheelweaving spider was observed during botanical and carabidolo- gical research conducted from May to November 2008. It was hand-collected and preserved in 75% alcohol. The specimen was kept in the first author’s private col- lection (ABC). Species was determined according to ROBERTS (1996) and nomencla- ture follows PLATNICK (2008). RESULTS AND DISCUSSION Two specimens of A. alsine were found during the study of the \on Mo~var peatland. The first specimen was observed in an alder forest – transitional peatbog ecoton (Carici elongatae-Alnetum glutinosae – Drosero-Caricetum stellulatae) on 26.08. Fig. 1. Geographical position of the Ðon Mo~var Botanical Reserve. Borders according to Natura 2000. M:\NATURA\natura_1-09\brigic.vp 24. lipanj 2009 9:55:50 Color profile: Disabled Composite 150 lpi at 45 degrees 42 Brigi}, A. et al.: Araneus alsine – a rare and likely threatened spider of the Croatian fauna 2008 (Gauss-Krueger coordinates 5571361, 5019689). The second specimen was ob- served and collected in the intermediate peatbog (Drosero-Caricetum stellulatae)on 18.09.2008 (GK: 5571372, 5019689) (Fig. 2A & 2B). Both specimens were found in a dry rolled silver birch leaf attached to moor grass (Molinia coerulea/arundinacea), at approximately one metre above the ground. The birch leaves were conically rolled, opened on the broader side and filled with silk on the opposite side. The spider Fig. 2.A & 2B. Araneus alsine (Walckenaer, 1802) (adult female), Ðon Mo~var Botanical Reserve peatland, Blatuša, Gvozd. leg. V. Šegota (photo: A. Brigi}) M:\NATURA\natura_1-09\brigic.vp 24. lipanj 2009 9:56:34 Color profile: Disabled Composite 150 lpi at 45 degrees Nat. Croat. Vol. 18(1), 2009 43 web was positioned beneath the leaf. The collected specimen is an adult female, 13 mm long (Fig. 2A & 2B). During the field studies, a number of rolled leaves were observed in September and October. However, they were not inhabited by any spi- ders. Four specimens of A. alsine from the end of 19th and the beginning of 20th cen- tury, all collected by Narcis Damin, are deposited in the spider collection of the De- partment of Zoology of the Croatian Natural History Museum (Jelenje, 02.07.1893, inventory number 1673; Zagreb, 10.04.1916, inv. nr. 1622; Osijek, inv. nr. 238, 1458, without dates). In addition, the species was recorded in Topusko (DAMIN, 1900) and in Kuzmica near Slavonska Po`ega in 1970 (RUCNER &RUCNER, 1995) (Fig. 3). Despite its wide distribution, this spider is often quite rare and only locally pres- ent. Furthermore, it can be easily overlooked (ROBERTS, 1996; BIERWIRTH, 1998). Sim- ilarly to the results presented here, in most studies the species was caught in small numbers, often less than 10 (BARTHEL &PLACHTER, 1995; SVATOÒ &PRÍDAVKA, 2000; KOMPOSCH, 2000) or only a single specimen (POLENEC 1958; KUNTNER &KOSTANJ[EK, 2000). This mesophilous species (BUCHAR, 1992; BUCHAR &RUg@I^KA, 2002) can be found mostly on moist forest clearings and meadows (HEIMER &NENTWIG, 1991; BARTHEL & PLACHTER, 1995; ROBERTS, 1996; BIERWIRTH, 1998; KOMPOSCH, 2000; PLATNICK, 2008). Fig. 3. Distribution of Araneus alsine in Croatia. Legend: ¡ – findings from the end of 19th century until 1916; l – findings from 1970 until 2008. M:\NATURA\natura_1-09\brigic.vp 24. lipanj 2009 9:56:46 Color profile: Disabled Composite 150 lpi at 45 degrees 44 Brigi}, A. et al.: Araneus alsine – a rare and likely threatened spider of the Croatian fauna WILLIAMS (2003) reported capturing A. alsine on a site including a mosaic of open boggy areas (blanket bog) within a conifer plantation.